A public-private repo. You may fork and whatever, but this is some custom Caddy middleware for a website. This interacts with Google calendar and is capable of sending email, creating PDFs, by filling out a text.Template and calling LaTeX.
It is also capable of creating invoices for tours.
See https://nlgids.london for the result.
Multiday events are not parsed, if you want to set a period as busy, you'll have to do this on a day to day basis.